FIx minor grammer issues

I wasn't sure how much changes you would consider so minor change suggestions for now.
Hope this is helpful.

A bigger suggestion would be to change the Policy header to Goals since that seems to fit the content, and make other adjustment under that section.
Let me know if you would be interested for suggestions!

Author: tockrock

README.md

@@ -19,9 +19,9 @@ The documents of master branch are as follows:
 
 Our goal of this project is to achieve that
 
-- **every AtCoder users** can use this library with **minimum efforts of studying about PC**
-- maximize convenience for **the usage in competitive programming**. We completely ignore other usages.
-- no bugs. This is a fantasy, but we pursue this.
+- Enable **every AtCoder users** to use this library with **minimum efforts of studying about PC**
+- Maximize convenience for **the usage in competitive programming**. We completely ignore other usages.
+- No bugs. This is a fantasy, but we pursue this.
 
 By this policy, we ignore some manners of C++ intentionally. For example,
 
@@ -46,7 +46,7 @@ We accept issues/PRs **only from AtCoder users**.
 
 We would appreciate it if you would report our mistakes like a typo, or, more importantly, bugs!
 
-As mentioned above, we haven't decided which way to go. Therefore we close feature requests for now.
+As mentioned above, we haven't decided which way to go. Therefore we are not accepting feature requests for now, and issues will be closed.
 
 ## Releases